In most existing highway toll collection systems around the world, vehicles are requested to stop at toll stations along the highway to pay tolls manually. Since the highway users have to stop their vehicles to pay the tolls at the toll stations and the transactions are carried out manually, the labor cost is kept high, time of the highway users is wasted, and air pollution is aggravated.
In addition, an automated ETC system may also be deployed over the lanes based on the dedicated short range communication (DSRC) protocol or the global positioning system (GPS) together with a mobile communication technique (for example, the general packet radio service (GPRS)) such that the ETC transactions can be automatically carried out.
However, because vehicles running in multiple lanes do not have to stick to specific lanes or slow down purposely, toll collection and law enforcement are made difficult. Thereby, multi-lane free flow ETC cannot be accomplished regardless of which ETC system (i.e., DSRC or GPS+GPRS)) is adopted.